Aggelopoulos Nikolaos C, Liebe Stefanie, Logothetis Nikos K, Rainer Gregor
Max Planck Institute for Biological Cybernetics Tuebingen, Germany.
Front Behav Neurosci. 2011 Nov 15;5:73. doi: 10.3389/fnbeh.2011.00073. eCollection 2011.
Acetylcholine (ACh) is a neurotransmitter acting via muscarinic and nicotinic receptors that is implicated in several cognitive functions and impairments, such as Alzheimer's disease. It is believed to especially affect the acquisition of new information, which is particularly important when behavior needs to be adapted to new situations and to novel sensory events. Categorization, the process of assigning stimuli to a category, is a cognitive function that also involves information acquisition. The role of ACh on categorization has not been previously studied. We have examined the effects of scopolamine, an antagonist of muscarinic ACh receptors, on visual categorization in macaque monkeys using familiar and novel stimuli. When the peripheral effects of scopolamine on the parasympathetic nervous system were controlled for, categorization performance was disrupted following systemic injections of scopolamine. This impairment was observed only when the stimuli that needed to be categorized had not been seen before. In other words, the monkeys were not impaired by the central action of scopolamine in categorizing a set of familiar stimuli (stimuli which they had categorized successfully in previous sessions). Categorization performance also deteriorated as the stimulus became less salient by an increase in the level of visual noise. However, scopolamine did not cause additional performance disruptions for difficult categorization judgments at lower coherence levels. Scopolamine, therefore, specifically affects the assignment of new exemplars to established cognitive categories, presumably by impairing the processing of novel information. Since we did not find an effect of scopolamine in the categorization of familiar stimuli, scopolamine had no significant central action on other cognitive functions such as perception, attention, memory, or executive control within the context of our categorization task.
乙酰胆碱（ACh）是一种通过毒蕈碱型和烟碱型受体起作用的神经递质，与多种认知功能及功能障碍有关，如阿尔茨海默病。据信它对新信息的获取有特别影响，当行为需要适应新情况和新的感觉事件时，这一点尤为重要。分类，即将刺激分配到某一类别中的过程，是一种也涉及信息获取的认知功能。此前尚未研究过ACh在分类中的作用。我们使用熟悉和新颖的刺激，研究了毒蕈碱型ACh受体拮抗剂东莨菪碱对猕猴视觉分类的影响。当控制了东莨菪碱对副交感神经系统的外周效应后，全身注射东莨菪碱会破坏分类表现。只有在需要分类的刺激此前未见过时才会观察到这种损害。换句话说，猕猴在对一组熟悉的刺激（它们在之前的实验中已成功分类的刺激）进行分类时，并未受到东莨菪碱中枢作用的损害。随着视觉噪声水平增加使刺激变得不那么突出，分类表现也会变差。然而，在较低连贯水平下，东莨菪碱并未对困难的分类判断造成额外的表现干扰。因此，东莨菪碱特别影响将新范例分配到已建立的认知类别中，大概是通过损害新信息的处理来实现的。由于我们未发现东莨菪碱对熟悉刺激分类有影响，在我们的分类任务背景下，东莨菪碱对其他认知功能如感知、注意力、记忆或执行控制没有显著的中枢作用。
